This invention relates to the field of cutting of fibrous material, such as velvet, particularly, but not exclusively, in relation to the use of fibrous material as light protection strips for containers for light sensitive material.
In the manufacture of containers for 35 mm film a metal strip of blanks is pressed into shape and notches cut at the required locations. A fibrous material, such as velvet, is used as light lock material for the containers. Once the slots in the strip of blanks have been cut a further machine applies strips of the light lock material to the blanks. The material has a fibrous pile and a semi-rigid base. The underside of the material has thermo-adhesive backing so that it sticks to the strip of container blanks. Before the strips of blanks can be separated into individual container blanks it is necessary to cut the material strips at the notch points.
In a typical conventional apparatus used to manufacture film cassettes the strips of light lock material are cut by cold rotary knives. It is also known to cut the strips by laser or by ultrasonic means. However, these latter two methods are extremely expensive.
When a cold knife is used to cut the fibrous strips the strands of fibers forming the pile are cut as well as the base fabric. This generates large quantities of loose fibers. These loose fibers are loosened from the base matrix. As there is insufficient adhesive to hold the fibers to the base they no longer have means of fixture and migrate and contaminate the production machinery. It will be appreciated that due to the large amount of loose fibers generated the equipment has to be regularly cleaned.
The present invention aims to provide a method and apparatus for cutting strips of fibrous material which reduces fiber strand liberation.
According to the present invention there is provided a method of cutting a material having a semi-rigid base and fibrous pile wherein fibers are removed from the vicinity of the cut prior to the cut being made.
Preferably, the fibers are removed by applying heat to the fibrous pile to vaporize contacted fibers. Adjacent fibers may be melted and fused together.
The invention further provides an apparatus for cutting a material having a semi-rigid base and fibrous pile including means for removing fibers at the location of the cut.
Preferably the means for removing fibers comprises vaporizing means for vaporizing fibers with which it comes into contact.
The vaporizing means may comprise a heated member, such as a rigid, non-rotating blade.
The blade may be heated by means of coiled heaters located within a recess of the blade.
The invention enhances the process of cutting fibrous material by removing and/or sealing together the strands of fibers prior to the cut being made through the base matrix. The cut can then be made at a later stage by conventional means. It is, however, possible that the process could be modified so that the means used to remove/seal the strands of fibers could also cut through the base matrix of the material. By vaporizing the fibers in the vicinity of the cut the amount of loose strands of fibers generated is dramatically reduced. Generation of less loose fibers leads to less downtime of the process equipment for cleaning and maintenance. This leads to increased productivity.
Existing machinery for producing film cassettes can readily be adapted to incorporate the invention. It is not necessary to build entirely new machines.